Manufacture of abrasive wheels



Sept. 5, 1939.

R. J. GooDNow Er Al. 2,172,243 i MNUFACTURE 0F ABHASIVE WHEELS FiledJune 16, 1938 2 Sheets-Sheet l Z/zZ/wlr's; /ardfaanaw i Doane/al .5.W607i! f SePt- 5, 1939. R. J. GooDNow ET AL 2,172,243

MANUFACTURE 0F ABRASIVE WHEELS Filed June 1e, 193s 2 sheets-sheet 2 NQSA@ Q WM I \w\ w 4 ...il t

@Quim @am @wel Patented Sept. 5, 1939 UNITED STATES PATENT OFFICEMANUFACTURE F ABRASIVE WHEELS Application June 16, 1938, Serial No.214,142

Claims.

The present invention relates to the manufacture oi abrasive wheels, andparticularly to a method of and apparatus for producing an abrasivewheel which has a uniform structure.

5 In the manufacture of abrasive elements, particularly wheels, theabrasive material is generally positioned in a mold made up of an innersleeve and an outer cylinder between which the abrasive material ispacked. End plates fitting between the sleeve and cylinder provide forcompacting the wheel material by pressing the end plates` toward eachother. This compacting, which exerts pressure in an axial direction onlydoes not necessarily provide a uniform compacting of the wheel material,as will be apparent.

Moreover the abrasive particles of the material rapidly wear away thecylindrical surfaces of the mold, especially adjacent to the corners ofthe end plates during the compressing of the wheel, and thus materiallyshorten the life of the mold. At the same time, as the cylindricalsurfaces of the mold are worn away, removal of the wheel from the moldwithout injury to the wheel becomes progressively more difficult, sincethe end portions oi the cylindrical elements of the molds are worn awayto a less degree than the central portions. The removal of the compactedwheel material through the end portion of slightly smaller diameternecessarily upsets the compact grain structure in the periphery of thewheel.

One of the principal objects of the present invention is to avoid theobjections above noted by compacting the wheel material radially andthus providing a mold which is separable radially of the compactedabrasive material.

Moreover, where abrasive Wheels having a substantial length as comparedto the diameter are molded, the abrasive action, by reason of theresistance of the grains of the abrasive material to movement, preventsa uniform compacting of the entire abrasive material within the mold sothat the ends of the wheel may be properly compacted, although thecentral part of the wheel being less properly compacted, will break downin use. Furthermore, with relatively long abrasive wheels, the inwardmovement of the end caps of the mold toward each other in compacting theabrasive material is necessarily substantial and the abra- 50 siveparticles wedge between the corners of the end caps and the cylindricalsurfaces of the mold, thereby resisting the compacting pressure andrapidly wearing away the mold surfaces. One of the objects of theinvention is to avoid this 55 difficulty by compacting the material inthe mold by radial pressure on the abrasive material rather than byaxial pressure.

A further feature of the invention is in the Iastening of a nut orsleeve, or other metallic element, within the abrasive wheelbypositively com- 5 pacting the material around the notches or grooves inthe periphery of the metallic element so that the element will bepositively held Within the wheel. By the use of the radial compactingpressure above referred to, the grains of the abrasive material arecompacted tightly around the metallic element.

Other and further objects and advantages of the invention will morefully appear from the following detailed description taken in connectionwith the accompanying drawings in which- Fig. 1 is a sectional viewthrough a mold embodying the invention.

Fig. 2 is a sectional view similar to Fig. 1, showing the action of themold under the compacting pressure.

Fig. 3 is a sectional view similar to Fig. l, showing the mold partsafter the compa/cting pressure is relieved.

Fig. 4 is a sectional view showing a different mold for forming conicalor tapered wheels in accordance with the invention.

Fig. 5 is a sectional view similar to Fig. 4, showing the mold of Fig. 4when the compacting pressure has been applied.

Fig. 6 corresponds to Figs. 4 and 5, showing the mold when thecompacting pressure has been relieved.

Like reference characters refer to like parts in the different figures.

With reference first to Fig. 1, the mold embodies a sleeve I having asubstantially cylindrical outer surface 2. An outer ring 3 having asubstantially cylindrical inner surface 4 is positioned around thesleeve I and a ring-shaped end cap 5 is positioned between the lowerends of the sleeve i and ring 3. An end cap 5 similar to the end cap 5is placed above the abrasive material in the mold after the latter hasbeen filled and the material is compressed by axial pressure on the endcaps 5 and 5'. In filling the mold, the ring 3 is generally heldslightly above the supporting surface S on which the mold is positionedby suitable blocks 1. Such mold structure is Well known and need not bedescribed in further detail.

In accordance with the present invention the abrasive material 8 withinthe mold is compacted by a radial pressure instead of, or in additionto, an axial pressure with the radial pressure uniformly distributedover the entire area of the abrasive material. To this end a sleeve 9 ofvery resilient material, such as tough rubber, is positioned around theouter surface of the sleeve I and in engagement therewith. The sleeve 9rests on the end cap 5 and is slightly longer in its normal state thanthe length of the finished abrasive wheel. A similar sleeve II), also ofresilient tough rubber, is positioned inside of the ring 3 and is alsoslightly longer than the length oi the finished wheel to be molded. Theabrasive material B is then positioned between the sleeves 9 and I9, theend cap 6 is placed in position, as shown in Fig. 1, and a compactingpressure is applied to the end caps 5 and 5, as indicated in Fig. 2, bythe arrows Il. Obviously, before the compacting pressure is applied, theblocks I are removed from beneath the ring 3.

The compacting pressure on the end caps 5 and 6 squeezes the rubbersleeves 9 and I0 and causes them to expand laterally, as indicated inFig. 2, thereby exerting a radial pressure on the abrasive material 8,the radial pressure being represented by arrows I2. 'I'he radialexpansion of the sleeves must be toward the abrasive material, since thering 3 and sleeve I prevent expansion in the opposite direction. Theabrasive material having been compacted to the desired length for thefinished abrasive wheel, this length being the spacing between the innersurfaces of the end caps 5 and E, the axial pressure on the end caps isrelieved and the rubber sleeves 9 and I9 assume their original position,thereby withdrawing radially of the compacted abrasive material to leavea space I3 between the inner surface of the sleeve I0 and the compactedabrasive material, and a corresponding space I4 between the outersurface of the sleeve 9 and the compacted abrasive material. The sleeveI, the ring 3, the top end cap 6 and the sleeves 9 and I0 may then beremoved without injury or damage to the compacted abrasive material. Thecompacted material is then ready to be placed in the curing oven.

It will be apparent that, by the above described structure, the wheelmaterial is compacted by a radial pressure and substantially all wear onthe mold is eliminated since the abrasive particles exert almost no wearon the rubber sleeve. It will be understood that the properties oi thesleeve I and ring 3, as well as the end caps 5 and B, must be variedfrom the standard mold structure to allow for the insertion of thesleeves 9 and I0 in order to produce the desired size 0f abrasive wheel,but such changes in shape from the standard mold are readily apparent.

With reference now to Figs. 4, 5, and 6, the mold shown is intended forthe compacting of a substantially conical abrasive wheel and at the sametime there is a provision for fastening into the abrasive wheel apermanent spindle. In these figures the mold comprises an outer ring I5cylindrical in form, and a bottom end cap I6 of a diameter to fit withinthe cylinder or ring I5. An upper end cap I1 is slidable within thecylinder or ring I5 and suitable blocks I9 hold the ring I5 slightlyabove the surface S on which the mold is positioned. Positioned withinthe ring I5 is an element I9 formed of tough resilient material, such asrubber, having its outer surface 29 cylindrical to fit within the ringI5 and having its inner surface 2I tapered to correspond approximatelyto the taper of the abrasive wheel. The element I9 is slightly longerthan the length of the finished abrasive wheel, as will be apparent.

In the use of this mold a pin 22, which is permanently mounted withinthe abrasive wheel, is positioned in a central bore 23 in the end capI6. The portion of the pin 22 which is embedded in the abrasive wheelmay have a groove 24 which is iilled with abrasive material during theformation of the wheel to provide a more permanent attachment of thewheel to the pin. The mold is then assembled, as shown in Fig. 4, andthe element I9 is lled with abrasive material 25 which may be slightlycompacted, if desired. The upper end cap Il is then placed in positionand the blocks I8 are removed. An axial pressure, represented by thearrows 26, is then applied to the end caps I6 and II to compact thewheel axially to the desired length. During this compacting the rubberelement I9 is compressed axially and therefore expands radially inwardlyto exert on the abrasive material 25 a radial compacting pressurerepresented by the arrows 2l, Fig. 5. This radial pressure is uniformover the entire surface of the abrasive material and it will be apparentthat this radial pressure assures a uniform compacting of the abrasivematerial. Moreover the radial pressure forces abrasive material into thegroove 24 for a more positive union between the pin and wheel.

After the compacting pressure is relieved, the resiliency of the rubberelement I9 causes it to assume its original or normal shape, as shown inFig. 6, thereby withdrawing the rubber radially from the compactedabrasive material to leave an annular space 28 entirely surrounding theabrasive material. Tne upper end cap Il, the element I9 and the ring I5may then be removed in readiness for curing the abrasive material.

It will be understood that the dimensions of the rubber element I9 mustbe so controlled as to assure a proper compacting of the abrasivematerial by the time that the material has been compacted axially to thedesired length. It will be further understood in connection with Figs. lto 3 inclusive, that in certain instances either the sleeve 9 or thesleeve I0 may be eliminated, since either sleeve by itself will providethe radial pressure desired. Where only one of the sleeves 9 or I9 isutilized, the compacted abrasive material remains in contact with themold surface opposite to the rubber sleeve and must be pressed from thatportion of the mold with which it engages. On the other hand the use ofa single rubber sleeve will assure a smooth face on the oppositecylindrical side of the finished wheel. Obviously, if either sleeve 9 orI0 is shaped other than a cylinder, as for example, the shape of thesleeve I9, a corresponding contour will be produced in the wheel whenmolded. Such sleeves can therefore be utilized in the molding of formedwheels, whose periphery must have a predetermined coniiguration, andsuch formed wheels can be molded in a conventional type of mold normallyused for cylindrical wheels.

We claim:

1. In the manufacture of abrasive wheels, the step which involvesplacing a resilient liner in a mold of a length greater than the lengthof the article being molded, and axially compacting the abrasivematerial and liner simultaneously to provide a radial compacting of thematerial.

2. In the manufacture of abrasive wheels in a mold comprising end capsand a cylindrical outer ring within which the end caps are movable, thesteps which involve placing a resilient liner in the mold, said linerbeing longer than the length of the article being molded and one surfaceof the liner corresponding approximately to the shape oi one surface ofthe article being molded, and axially compacting the abrasive materialand liner simultaneously to provide, by the radial expansion of theliner, a radial compacting of the abrasive material.

3. In the manufacture of conical abrasive Wheels in a mold comprisingend caps and a cylindrical outer ring within which the end caps aremovable, the steps which involve placing a. resilient liner in the mold,said liner being longer than the length of the article being molded andthe inner surface of the liner being conical, and axially compactng theabrasive material and liner simultaneously to provide, by the radialexpension of the liner, a radial compacting of the abrasive material.

4. In the manufacture oi abrasive wheels in a mold comprising end caps,a cylindrical outer ring and a central sleeve, said end caps beingpositioned between the sleeve and the outer ring and movable axiallythereof. the steps which involve placing a resilient liner in the mold,said liner being longer than the length of the article being molded andextending axially of the mold between the end caps, one surface of theliner being engageable with the abrasive material in the mold, andaxially compacting the abrasive material and liner simultaneously toprovide, by the radial expansion of the liner, a relative compacting ofthe abrasive material.

5. In the manufacture of abrasive wheels in a mold comprising end caps,an outer ring having a cylindrical inner surface and an inner sleevehaving an outer cylindrical surface, said end caps being positionedbetween said sleeve and ring and movable axially thereof, the stepswhich involve placing a resilient liner in the mold in engagement withone of said cylindrical surfaces, said liner being longer than thelength of the article being molded, and axially compacting the abrasivematerial and liner simultaneously to provide by the radial expansion ofthe liner, a radial compactlng o1' the abrasive material.

ROLAND J. GOODNOW. DONALD B. WILSON.

CERTIFI GATE 0F CORREO TI ON Patent No. 2,172,245

September 5, 1959- ROLAND J. GOODNON, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 50, for the word "properties" read proportions;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the r'ecord of the ease in thePatent Office.

Signed and sealed this 5rd day of October, A. D. 1959.

(Seal) Henry Van Aredale Acting Conmissioner of Patents.

the mold, said liner being longer than the length of the article beingmolded and one surface of the liner corresponding approximately to theshape oi one surface of the article being molded, and axially compactingthe abrasive material and liner simultaneously to provide, by the radialexpansion of the liner, a radial compacting of the abrasive material.

3. In the manufacture of conical abrasive Wheels in a mold comprisingend caps and a cylindrical outer ring within which the end caps aremovable, the steps which involve placing a. resilient liner in the mold,said liner being longer than the length of the article being molded andthe inner surface of the liner being conical, and axially compactng theabrasive material and liner simultaneously to provide, by the radialexpension of the liner, a radial compacting of the abrasive material.

4. In the manufacture oi abrasive wheels in a mold comprising end caps,a cylindrical outer ring and a central sleeve, said end caps beingpositioned between the sleeve and the outer ring and movable axiallythereof. the steps which involve placing a resilient liner in the mold,said liner being longer than the length of the article being molded andextending axially of the mold between the end caps, one surface of theliner being engageable with the abrasive material in the mold, andaxially compacting the abrasive material and liner simultaneously toprovide, by the radial expansion of the liner, a relative compacting ofthe abrasive material.

5. In the manufacture of abrasive wheels in a mold comprising end caps,an outer ring having a cylindrical inner surface and an inner sleevehaving an outer cylindrical surface, said end caps being positionedbetween said sleeve and ring and movable axially thereof, the stepswhich involve placing a resilient liner in the mold in engagement withone of said cylindrical surfaces, said liner being longer than thelength of the article being molded, and axially compacting the abrasivematerial and liner simultaneously to provide by the radial expansion ofthe liner, a radial compactlng o1' the abrasive material.

ROLAND J. GOODNOW. DONALD B. WILSON.

CERTIFI GATE 0F CORREO TI ON Patent No. 2,172,245

September 5, 1959- ROLAND J. GOODNON, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 50, for the word "properties" read proportions;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the r'ecord of the ease in thePatent Office.

Signed and sealed this 5rd day of October, A. D. 1959.

(Seal) Henry Van Aredale Acting Conmissioner of Patents.

